The present invention relates to an optical multiplexer/demultiplexer comprising an imaging lens and a reflection grating of the type disclosed in U.S. application Ser. No. 771,451 filed Aug. 30, 1985.
Several embodiments are explained in the aforementioned application. In those embodiments, light beams are guided to the respective inputs/outputs by optical fibers which make different angles with the perpendicular to the reflection grating. In the manufacturing process, accurate adjustment of the optical fibers is complicated.